The present technology relates to a recording device that carries out recording on an optical recoding medium, and particularly is suitably applied to a recording device in which first light that serves as recording light and second light that is different from the first light are applied and, as stray light associated with emission of the first light leaks into the second light when the second light is received, a stray light component is superimposed on a playback signal of the second light. Further, the present technology relates to a method for canceling a stray light signal component suitably applied to such a recording device.
As an optical recording medium on which recording or playback of a signal is carried out through light irradiation, a so-called optical disc recording medium (hereinafter, simply referred to as an optical disc in some cases) such as, for example, a CD (Compact Disc), a DVD (Digital Versatile Disc), and a BD (Blu-ray Disc: (R)) is widely available.
In a recording device that carries out recording on an optical disc, tracking servo control is carried out to cause a beam spot of irradiation light to follow a track formed on the optical disc.
To be more specific, a guide groove such as a pregroove is formed in advance in a typical recordable optical disc, and a tracking servo is carried out at the time of recording such that a recording spot follows the guide groove. Through this, recording can be carried out without a mark array intersecting with each other while eliminating an influence of the disc being eccentric or the like.
An optical disc in which a guide groove is not formed in a recording layer has been being developed in recent years. Not forming a guide groove in a recording layer leads to advantages such as reduction in the manufacturing costs to be incurred, for example, by multilayering.
Unlike a typical optical disc in which a guide groove is formed, the tracking servo may not be carried out on such an optical disc using recording light.
Thus, it is contemplated that recording on an optical disc in which a guide groove is not formed in the recording layer is carried out through a so-called ATS (Adjacent Track Servo).
The ATS was originally being considered for a self-servo track writer (SSTW) in a hard disc drive.
FIG. 7 is a descriptive view of the ATS.
As shown in FIG. 7, in the ATS, a recording spot Swr and an adjacent track servo spot Sats (hereinafter, abbreviated to an ATS spot) are formed on a recording layer. The spot Swr and the spot Sats are formed by irradiating a recording surface 100 of the recording layer with respective light beams therefor through a common objective lens 101, as shown in FIG. 8. Here, a distance between the spots is fixed at a predetermined length.
As shown in FIG. 7, in the ATS, provided that the recording spot Swr is a preceding spot (that is, an outer peripheral side in a case where a direction in which the recording progresses is from the inner periphery to the outer periphery) and the ATS spot Sats is a following spot, the tracking servo is carried out with the ATS spot Sats on a mark array that is formed by the recording spot Swr. That is, tracking servo control of the objective lens 101 is carried out such that the ATS spot Sats follows a track that is behind, by a single track, a track on which the recording spot Swr is formed.
To be more specific, such ATS can be realized by generating a tracking error signal based on reflection light from the ATS spot Sats and by driving a lens actuator 102 shown in FIG. 8 based on the tracking error signal to control the position of the objective lens 101.
Through such ATS, even when a guide groove is not formed in the recording layer, a signal can be recorded on the recording surface 100 at a pitch in accordance with spacing between the spot Swr and the spot Sats. (See, for example, Japanese Patent Laid-Open No. 2008-108325 and Japanese Patent Laid-Open No. 2005-332453.)